The present invention relates to an acceleration sensor and more particularly concerns an acceleration sensor that detects an acceleration in one direction (acceleration in linear motion).
Conventionally, small-size acceleration sensors of various types for detecting acceleration have been put into practical use. For example, with respect to cantilever-type acceleration sensors, the following acceleration sensors have been known: those having a construction in which a piezoelectric element is cantilevered and supported by a support member so that a voltage caused by a distortion in the piezoelectric element in response to a generated acceleration is sensed and the acceleration is consequently detected; and those having a construction in which a semiconductor is cantilevered and supported by a support member so that a change in resistivity due to a distortion in the semiconductor in response to a generated acceleration is sensed and the acceleration is consequently detected. Moreover, other acceleration sensors have been proposed in which the inertia of an optical fiber gyro is utilized so as to detect an acceleration.
In the case of the above-mentioned cantilever-type acceleration sensors, in order to distort the structural element (piezoelectric element or semiconductor), it is necessary to increase the mass of the structural element so as to obtain a greater stress. Therefore, in order to enhance the detection precision, it is inevitable to make the acceleration sensors heavier and bulkier. Moreover, in the case of the acceleration sensor using an optical fiber gyro, when the diameter of the optical fiber is made smaller in an attempt to make the acceleration sensor smaller, the detection precision tends to deteriorate. Furthermore, since it is not possible to separate an acceleration in one direction and a rotation angular velocity by using a single acceleration sensor, there are still some problems to be solved before this is put into practical use.